1. Field of the Invention
The present invention relates to an image forming apparatus comprising a facsimile memory for storing transmission/reception data by a memory transmission/reception function of a facsimile and a copying memory for storing copying data or externally inputted data by a copying/printing function.
2. Description of the Related Art
In a conventional digital image forming apparatus which is called a digital composite machine and provided with a fax mode and a copy mode (copying function or printing function), an operation panel for setting conditions of the fax and copy modes is integrated with a control function thereof.
However, although the control function is integrated with the operation panel, memories associated with the respective functions individually work. Therefore, in the fax mode, when a memory for memory reception becomes full, a reception state is put into a busy state, or data not yet outputted is erased because reception data in the memory is overwritten. Such a phenomenon frequently happens particularly when recording sheets such as sheets of paper in a paper-feed cassette or rolls of paper run out in the nighttime or when a supply item such as toner is replaced.
Further, in the copy mode, a technique utilizing memory copying for increasing the speed of reading documents in image processing is used, however, when a memory for document information becomes full, reading of the following document is stopped, and therefore the document reading speed cannot be increased.
Japanese Unexamined Patent Publication JP-A 10-243175 (1998) discloses a technique of checking the remaining free area of a memory and controlling so as to allow a copy operation when a document size read in the following operation is within the remaining free area of the memory, whereas so as not to accept a reading request when the document size is larger.
As mentioned above, the conventional digital image forming apparatus checks the remaining free area of a memory and controls so as to allow a copy operation when a document size read in the following operation is within the remaining free area of the memory, whereas so as not to accept a reading request when the document size is larger. Therefore, the apparatus raises a problem such that when a memory has only a little or no free area, the following operation can not be carried out, or data not yet outputted is erased because of overwriting.